1. Field of the Invention
The application relates to a backlight module, especially a direct type backlight module with optical control film.
2. Description of the Prior Art
In recent years, the technology of liquid crystal display device is gradually mature. With the increasing in consumer's preferences and requirements, the liquid crystal display device also gradually toward a thin type. To achieve the purpose of the thin type, each component thickness of the liquid crystal display device is required to be reduced, such as a display panel, an optical film, and a backlight module. Wherein the backlight module needs a light mixing space so that the thickness usually is larger; therefore it becomes the main target to be reduced.
FIG. 1A is a schematic diagram of a conventional backlight module. It comprises a supporting board 24, a porous reflecting sheet 22, a lower reflecting sheet 26 and a diffusing plate 23. A plurality of light sources 25 are disposed on the supporting board 24. The porous reflecting sheet 22 is disposed above the light sources 25 to distribute the light generated from the light sources 25. Wherein the distance between the porous reflecting sheet 22 and the diffusing plate 23 is H1, and the distance between the porous reflecting sheet 22 and the top surface of the light source 25 is H2. Multiple light emitting holes are disposed on the porous reflecting sheet 22. Accordingly, the porous reflecting sheet 22 can optionally reflect the light from the light source 25, or allow the light to pass through, to distribute the light to uniform the backlight.
However, when designing a thinner module, as shown in FIG. 1B, can reduce the distance H1 between the porous reflecting sheet 22 and the diffusing plate 23 to reduce the thickness. Because the first time light scatters from the light emitting holes, the restriction of the direct emitting area of the first time light is oversize, that is, the area (without the light emitting holes) where the light source 25 projects to the porous reflecting sheet 22 is oversize. The dark area is occurred above the light source corresponding to the diffusing plate 13.